1. Technical Field
The present disclosure relates to a liquid crystal display panel and a liquid crystal display apparatus having the liquid crystal display panel. More particularly, the present disclosure relates to a liquid crystal display panel including an inorganic vertical alignment (VA) layer with improved adhering properties and a liquid crystal display apparatus having the liquid crystal display panel.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) apparatus includes a liquid crystal layer. The liquid crystal layer includes liquid crystal molecules having an anisotropic permittivity, and the liquid crystal molecules are injected between substrates to form the liquid crystal layer. When an electric field is applied to the liquid crystal layer, an amount of a light transmitted through the substrates is controlled by adjusting an intensity of the electric field, so that the liquid crystal display apparatus displays an image.
The liquid crystal molecules in the liquid crystal layer are aligned in a predetermined direction at an initial state. However, an alignment direction of the liquid crystal molecules is changed when the electric field is applied to the liquid crystal layer to change the amount of the light transmitted through the liquid crystal layer.
In order to align the liquid crystal molecules, an alignment recess is formed on an alignment layer by using a roller with cloth such as velvet after a resin, for example, polyimide-based resin, is coated on the substrate in a slice thickness so as to form the alignment layer. The above-described process is referred to as a “rubbing process” in that the alignment recess is formed on the alignment layer by rubbing the substrate using the roller with cloth.
The rubbing process generates a considerable amount of particles on the alignment layer to contaminate the alignment layer when rubbing the alignment layer, so that an additional cleaning process for cleaning the particles from the alignment layer is required. In addition, the rubbing process is performed through friction between the alignment layer and a rubbing cloth of the roller so as to form the rubbing recess on the alignment layer, so that static electricity is generated on a surface of the alignment layer. Therefore, when the alignment layer is excessively rubbed, a large amount of static electricity is generated on the surface of the alignment layer, so that a thin film transistor disposed beneath the alignment layer is damaged.
Large display apparatuses having a size larger than forty inches have become popular. Considering the above trend in the display industry, the rubbing process is difficult to be employed in manufacturing a large scale display panel because of non-uniformity of the alignment and a generation of static electricity resulting from the friction on the alignment layer.
Attempts have been made to develop a non-contact process such as a photo-alignment method capable of replacing a contact-type alignment method.
As the liquid crystal display panel is scaled up, issues related to characteristics such as viewing angle, an afterimage, and response speed arise. The issues related to the viewing angle may be overcome using a patterned vertical alignment (PVA) type alignment layer. An afterimage can be generated because the alignment layer absorbs impurity ions at the surface of the alignment layer. Also, the response speed of the liquid crystal molecules in the electric field is improved by forming a pretilt angle to the liquid crystal molecules when initially aligning the liquid crystal molecules.
Particularly, the PVA type alignment process essentially requires a vertical alignment (VA) layer. A method of forming the alignment layer can be classified into a parallel alignment type such as a twisted nematic (TN) type and an in-plane switch (IPS) type, etc., and a vertical alignment type such as a vertical alignment (VA) type and a patterned vertical alignment (PVA) type, etc.
A non-contact type process for an inorganic alignment layer for a vertical alignment has not been developed. The inorganic alignment layer generally has a low adhering characteristic, so that an additional adhering member may be used between the substrate and the alignment layer. However, the adhering member is an additional member, so that when light transmittance of the adhering member is low, brightness of the liquid crystal display apparatus is also lowered. Hence, the adhering member requires enhanced light transmittance.
In the large-sized liquid crystal display apparatus, although the non-contact type inorganic alignment layer is used, the non-contact type inorganic alignment layer is easily separated from the substrate, so that the non-contact type inorganic alignment layer has a low stability.
Therefore, an adhering member is required to improve the stability of the alignment layer. Further, the adhering member is an additional layer, so that the adhering member enhancing the adhering property requires sufficient light transmittance capability to prevent the deterioration of brightness of the liquid crystal display apparatus.